WASHINGTON — Francis Dennis Sr., 82, a former Liberian ambassador to the United States and other countries who later held an academic post at Howard University, died Sept. 20 of cancer at his home in Falls Church, Va.

Dennis began his diplomatic career in 1955 and first came to Washington in 1959 as an official at the Liberian Embassy. In 1962, he was assigned to London as counselor and deputy chief of mission at his country’s embassy in Britain.

He served as ambassador to the Ivory Coast from 1968 to 1972, when he was appointed Liberia’s first ambassador to the Soviet Union. In 1976, he returned to Washington as ambassador to the United States and Canada. In 1979 and 1980, he moved to London and served as his country’s ambassador to the United Kingdom, the Vatican and the Scandinavian nations.

He retired from the diplomatic service late in 1980 and returned to the Washington area. He helped establish Howard University’s department of international affairs and served as associate director for eight years. He was also a consultant to businesses with dealings in Africa.

Dennis was born in Monrovia, Liberia, and graduated from the University of Liberia in 1950. He received a diploma from the Liberian foreign service institute and graduated in 1955 from the University of Liberia’s law school.

He represented his country at many international conferences, including meetings of the United Nations and the International Maritime Organization.

He helped develop the ambassador’s library at the Liberian Embassy in Washington and donated many of his personal papers to the library.

Dennis was a member of the First Baptist Church of the City of Washington, taught Sunday school and chaired several committees. He was a member of the Baptist Joint Committee for Religious Liberty, the Baptist World Alliance and served on committees of the D.C. Baptist Convention.

He maintained a second home in Careysburg, Liberia, and traveled widely throughout the world.

Survivors include his wife of 55 years, Evangeline Morris Dennis, of Falls Church; four children, Francis Dennis Jr., of Monrovia, Florence Dennis-Huskin, of Alexandria, Va., and Beryl Dennis and Baromi Albert Dennis, both of Falls Church; a brother, Norwood Dennis Jr., of Columbia, Md.; three sisters, Laura Dennis-Johnson, of Plano, Texas, Williette Adorkor, of Durham, N.C., and Catherine Nylander, of Buffalo; two grandchildren; and a great-granddaughter.